diff --git a/modules/oe_whitelabel_helper/src/EuropeanUnionLanguages.php b/modules/oe_whitelabel_helper/src/EuropeanUnionLanguages.php
deleted file mode 100644
index 9ac60d58512bcf24f145222c85cf20adc9fdbdd4..0000000000000000000000000000000000000000
--- a/modules/oe_whitelabel_helper/src/EuropeanUnionLanguages.php
+++ /dev/null
@@ -1,120 +0,0 @@
-<?php
-
-declare(strict_types = 1);
-
-namespace Drupal\oe_whitelabel_helper;
-
-/**
- * Helper class storing European Union languages information.
- *
- * @see https://github.com/openeuropa/oe_theme/blob/HEAD/modules/oe_theme_helper/src/EuropeanUnionLanguages.php
- */
-class EuropeanUnionLanguages {
-
-  /**
-   * List of European Union languages.
-   *
-   * Each entry includes:
-   *
-   * - The language name in English
-   * - The language name in its native form
-   * - The internal language ID, used on URLs, asset names, etc.
-   *
-   * @var array
-   */
-  protected static $languages = [
-    'bg' => ['Bulgarian', 'български', 'bg'],
-    'cs' => ['Czech', 'čeština', 'cs'],
-    'da' => ['Danish', 'dansk', 'da'],
-    'de' => ['German', 'Deutsch', 'de'],
-    'et' => ['Estonian', 'eesti', 'et'],
-    'el' => ['Greek', 'ελληνικά', 'el'],
-    'en' => ['English', 'English', 'en'],
-    'es' => ['Spanish', 'español', 'es'],
-    'fr' => ['French', 'français', 'fr'],
-    'ga' => ['Irish', 'Gaeilge', 'ga'],
-    'hr' => ['Croatian', 'hrvatski', 'hr'],
-    'it' => ['Italian', 'italiano', 'it'],
-    'lt' => ['Lithuanian', 'lietuvių', 'lt'],
-    'lv' => ['Latvian', 'latviešu', 'lv'],
-    'hu' => ['Hungarian', 'magyar', 'hu'],
-    'mt' => ['Maltese', 'Malti', 'mt'],
-    'nl' => ['Dutch', 'Nederlands', 'nl'],
-    'pl' => ['Polish', 'polski', 'pl'],
-    'pt-pt' => ['Portuguese', 'português', 'pt'],
-    'ro' => ['Romanian', 'română', 'ro'],
-    'sk' => ['Slovak', 'slovenčina', 'sk'],
-    'sl' => ['Slovenian', 'slovenščina', 'sl'],
-    'fi' => ['Finnish', 'suomi', 'fi'],
-    'sv' => ['Swedish', 'svenska', 'sv'],
-  ];
-
-  /**
-   * Returns a list of language data.
-   *
-   * This is the data that is expected to be returned by the overridden language
-   * manager as supplied by the OpenEuropa Multilingual module.
-   *
-   * @return array
-   *   An array with language codes as keys, and English and native language
-   *   names as values.
-   */
-  public static function getLanguageList(): array {
-    return self::$languages;
-  }
-
-  /**
-   * Assert whether the given language is a European Union one.
-   *
-   * @param string $language_code
-   *   The language code as defined by the W3C language tags document.
-   *
-   * @return bool
-   *   Whereas the given language is a European Union one.
-   */
-  public static function hasLanguage(string $language_code): bool {
-    return isset(self::$languages[$language_code]);
-  }
-
-  /**
-   * Get the language name in English given its W3C code.
-   *
-   * @param string $language_code
-   *   The language code as defined by the W3C language tags document.
-   *
-   * @return string
-   *   The language name in English if any, an empty string otherwise.
-   */
-  public static function getEnglishLanguageName(string $language_code): string {
-    return self::$languages[$language_code][0] ?? '';
-  }
-
-  /**
-   * Get the native language name given its W3C code.
-   *
-   * @param string $language_code
-   *   The language code as defined by the W3C language tags document.
-   *
-   * @return string
-   *   The native language name if any, an empty string otherwise.
-   */
-  public static function getNativeLanguageName(string $language_code): string {
-    return self::$languages[$language_code][1] ?? '';
-  }
-
-  /**
-   * Get the internal language code given its W3C code.
-   *
-   * Internal language codes may differ from the standard ones.
-   *
-   * @param string $language_code
-   *   The language code as defined by the W3C language tags document.
-   *
-   * @return string
-   *   The internal language code if any, an empty string otherwise.
-   */
-  public static function getInternalLanguageCode(string $language_code): string {
-    return self::$languages[$language_code][2] ?? '';
-  }
-
-}
diff --git a/modules/oe_whitelabel_helper/src/TwigExtension/TwigExtension.php b/modules/oe_whitelabel_helper/src/TwigExtension/TwigExtension.php
index 944b17e5fa625af94525c1631f9d1a6d2eb700e2..e667825177985d5331d24f9d741dfb4a5b50f1a8 100644
--- a/modules/oe_whitelabel_helper/src/TwigExtension/TwigExtension.php
+++ b/modules/oe_whitelabel_helper/src/TwigExtension/TwigExtension.php
@@ -6,7 +6,6 @@ namespace Drupal\oe_whitelabel_helper\TwigExtension;
 
 use Drupal\Core\Cache\CacheableDependencyInterface;
 use Drupal\Core\StringTranslation\PluralTranslatableMarkup;
-use Drupal\oe_whitelabel_helper\EuropeanUnionLanguages;
 use Drupal\Core\Url;
 use Twig\Extension\AbstractExtension;
 use Twig\TwigFilter;
@@ -37,7 +36,6 @@ class TwigExtension extends AbstractExtension {
   public function getFilters(): array {
     return [
       new TwigFilter('bcl_timeago', [$this, 'bclTimeAgo']),
-      new TwigFilter('to_internal_language_id', [$this, 'toInternalLanguageId']),
     ];
   }
 
@@ -184,21 +182,4 @@ class TwigExtension extends AbstractExtension {
     return $block_plugin->build();
   }
 
-  /**
-   * Get an internal language ID given its code.
-   *
-   * @param string $language_code
-   *   The language code as defined by the W3C language tags document.
-   *
-   * @return string
-   *   The internal language ID, or the given language code if none found.
-   */
-  public function toInternalLanguageId(string $language_code): string {
-    if (EuropeanUnionLanguages::hasLanguage($language_code)) {
-      return EuropeanUnionLanguages::getInternalLanguageCode($language_code);
-    }
-
-    return $language_code;
-  }
-
 }
diff --git a/modules/oe_whitelabel_multilingual/oe_whitelabel_multilingual.module b/modules/oe_whitelabel_multilingual/oe_whitelabel_multilingual.module
index 1dc9264e18018eb5f766cd521a7382da0ec50495..85fdf74f758967d9e56ded9a7b72b1b0b8848dc5 100755
--- a/modules/oe_whitelabel_multilingual/oe_whitelabel_multilingual.module
+++ b/modules/oe_whitelabel_multilingual/oe_whitelabel_multilingual.module
@@ -8,7 +8,7 @@
 declare(strict_types =  1);
 
 use Drupal\Component\Utility\Html;
-use Drupal\oe_whitelabel_helper\EuropeanUnionLanguages;
+use Drupal\oe_bootstrap_theme_helper\EuropeanUnionLanguages;
 
 /**
  * Implements hook_preprocess_links().
diff --git a/oe_whitelabel.theme b/oe_whitelabel.theme
index d6ecce13baf1bd8f2ae11197c9e6080dee659b70..6be05efd19aac9b9da2c23fe12627f36130b6e1b 100644
--- a/oe_whitelabel.theme
+++ b/oe_whitelabel.theme
@@ -9,8 +9,8 @@ declare(strict_types = 1);
 
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Url;
+use Drupal\oe_bootstrap_theme_helper\EuropeanUnionLanguages;
 use Drupal\oe_whitelabel\DocumentMediaWrapper;
-use Drupal\oe_whitelabel_helper\EuropeanUnionLanguages;
 
 // Include all files from the includes directory.
 $includes_path = __DIR__ . '/includes/*.inc';